Low-voltage industrial electrical systems having high currents and power levels can use specific devices, commonly known in the art as automatic power circuit breakers.
Automatic power circuit breakers can be designed for the correct operation of the electrical system in which they are inserted and the loads connected to the circuit breakers. For example, circuit breakers can help ensure the nominal current needed for the various users, allow correct insertion and disconnection of the loads with respect to the circuit, protect the loads against abnormal events such as overloading and short-circuits by opening the circuit automatically, and allow disconnect between the protected circuit by galvanic separation or by the opening of suitable contacts in order to achieve full isolation of the load with respect to the electric power source.
Known circuit breakers can be available according to various industrial embodiments, and can include one or more electrical poles having each at least one fixed contact and a corresponding movable contact which can be reciprocally coupled to/separated from each other.
The actuation of the movable contacts can be realized by controller, which can include a mechanism, which can include, for example, pre-charged opening springs, and a rotating shaft which can be triggered by the mechanism and can be operatively connected to the mobile contacts of the various poles by a suitable kinematic chain.
The actuating shaft can be connected, for example, at its end parts, to walls or flanks of the circuit breaker, in such a way that the flanks can mechanically support the shaft while allowing its rotation.
The mounting of the shaft can be important for the proper working of the whole circuit breaker. For example, the shaft should be mounted not only as easily as possible, but also very precisely because its mounted position can directly influence the correct position of the movable contacts among the various poles and relative to the correspondingly associated fixed contacts.
To address this issue, some adjustment mechanisms have been introduced, which can be positioned directly on the mounting flanks or walls of the circuit breaker and which can allow the adjustment of the position of the actuating shaft and therefore of the movable contacts of the various poles.
Although such solutions properly perform the desired functionalities, further improvements, for example, in regards to mounting and final positioning can be desirable.
In addition, such circuit breakers under fault conditions, for example, short-circuits, the flowing current must be interrupted as quickly as possible and therefore the movable contacts should quickly separate from the fixed contacts.
Various solutions have been adopted, some of which can be also used in combination.
For example, the current can be forced to follow a given path so that, when a short circuit occurs, electrodynamic repulsion forces can occur between the contacts. These repulsion forces can generate a thrust that can help increase the separation speed of the moving contacts with respect to the fixed contacts.
Another solution can Increase the energy accumulated in the opening springs of the mechanism, which can be delivered to the actuating shaft and the movable contacts.
Whichever solution is adopted, despite contributing to the generation of the thrust useful for contacts separation, the solution ends up in having a moving contact structure, which can reach the end of its stroke at high speed and therefore with high energy, and which can cause violent impacts of the moving equipment against other parts of the circuit breaker. For example, the moving contacts can bounce back towards the fixed contacts, thus bringing about undesirable restrikes of the electric arc.
To contrast this possibility, known solutions use additional anti-rebound mechanisms to latch the moving contacts in the open position.
However, when the position of the actuating shaft is adjusted, misalignments of the shaft can occur with respect to the anti-rebound mechanism, thus jeopardizing its proper latching function, which can render the presence of the latching mechanism useless.